I often hear that KDE is the heaviest desktop environment and GNOME is a little bit lighter than it. The minimum system requirements people offer for GNOME is often lower than that for KDE.

When it comes to building light desktops, people often reccomend choosing gtk apps and staying away from Qt as much as possible.

However, according to what I see, that doesn't seem to be quite true.

I installed GNOME by emerging gnome-light to get rid of apps I dont need. That machine was a Celeron 667MHz, 256MBs RAM. The desktop loads faster, but the issue i've always had with GNOME's menus is still there. They are sluggish. When I click on a menu, sometimes it lags a bit. And when it pops down for the first time, I often see icons drawing one by one. I have this problem with gtk apps in general. There always seems to be some weird lagginess with them.

I haven't tried KDE a lot. Actually I installed it accidentally on FreeBSD in the past (on the same machine i tried GNOME). I installed KDevelop and made some mistakes in choosing options, so it pulled the whole (basic) KDE as a dependency. Anyway, I was surprise to find that it was quite useable. I disabled most of the eye candies, only allowing a wallpaper or so. KDE apps starts up a bit faster than GNOME apps in GNOME. The most important thing is that the menus were way more responsive, just like in Windows. About resources, the 2 desktops take roughly the same.

I don't know if this is just my perception or everybody else is experiencing the same things. If so, why do I hear so often that GTK apps are lighter than Qt? Or KDE is more bloated than GNOME?

I don't mean to start any war here. I just want to know if this is a misconception or there's more to the term "lightweight" than just responsiveness.